Although it can also be applied to any desired micromechanical components, the present disclosure and the problems it addresses are explained on the basis of integrated microfluidic components.
Integrated microfluidic components, for example lab-on-a-chip systems in medical technology, often consist of a polymeric layer structure with enclosed microfluidic structures, such as for example channels and chambers.
Microfluidic components based on polymeric layer systems are versatile in their use on account of the flexible machining and connecting technologies and are a very good platform for realizing disposable components thanks to low costs. To increase the control over processes in complex microfluidic systems, basic information on the physical state of the fluids in such systems is indispensable. Apart from the temperature, the pressures in microfluidic cavities or channels is of importance in particular, in order to be able to set exact flow rates, to be able to detect the blockage of a channel and to monitor the function of valves or pumps.
DE 10 2009 000 529 A1 describes a system for measuring pressure with a measuring channel that is open at one end, a connection with the liquid existing at the open end and a gas being enclosed at the closed end. When there is an increase in the pressure, gas is compressed and the gas-liquid boundary surface is displaced. By observing the meniscus, the change in volume can be determined and, if the initial pressure is known, the current pressure can be determined by applying the Boyle-Mariotte law. For detecting the position of the meniscus, a method which assesses the properties of a light beam that has crossed through the region of the likely position of the meniscus with the aid of deflecting mirrors is proposed.
In Kohl, et al., A Microfluidic Experimental Platform with Internal Pressure Measurements, Sensors and Actuators A 118, (2005), pages 212 to 221, a silicon-based pressure sensor is presented. In it, the increase in the pressure deflects a silicon membrane, the deflection being determined by way of the reflection of a light beam.
Micromachined Channel/Pressure Sensor Systems for Microflow Studies, J. Liu et al., 7th International Conference on Solid-State Sensors and Actuators (Transducers '93) describes a silicon-based microfluidic channel with connected piezoresistive pressure sensors.
DE 10 2008 002 336 A1 discloses a pinch valve and a method for producing it, the pinch valve being used in microfluidic systems.